238 
FERTILIZERS. 
ment; and here the inquiry very properly comes up for consideration, what amount of lime is 
sufficient for all ordinary purposes 1 It is less than is usually supposed by farmers; one per 
cent of lime is enough, if we may rely upon the products of a soil which does not contain 
more than that quantity, for it is true that soils, where no larger amount than this is found, 
yield fine crops; when reduced to one half of one per cent, it is not really discerned in the 
diminution of the products. We have no calcareous soils in New-York or New-England, 
except in very limited areas. The limestones, as they occur in this country, are hard : the 
dolomites in the Taconic system and limestones denominated primary, are often friable, hence 
the debris is spread a few yards, and forms a soil composed entirely of granulated limestone.* 
But the soil directly upon our principal limestones rarely contain two per cent of lime. Our 
limestone soils are good, but not because they contain lime in so much greater abundance than 
other soils, but because their structure favors, usually, their drainage; they are usually loam 
soils, especially where the limestone is dark colored. We are not to infer that, because the 
soil is based on limestone that it is a calcareous soil, which seems to be the common opinion 
of our farmers. 
To conclude, lime is an aliment of plants, and is required as such; it supplies, in its sub¬ 
caustic state, carbonic acid, another element of great importance. Carbonic acid is an efficient 
solvent of rocks containing phosphoric acid and the alkalies. If the acid is set free, it may be 
dissolved in the water and absorbed directly; and it may also act as a solvent on the particles 
composing the soil, and enter thereby into new combinations, and become, in these forms the 
food of plants. Lime sets free the alkalies by decomposing the silicates of potash and soda. 
Lime should, in general, be laid on soils in combination with organic acids, or in the form 
of compost; layers of weeds, straw or turf, alternating with the refuse matters which may be 
collected, both animal and vegetate, and sprinklings of lime. In these artificial forms it seems 
to be converted into the food of plants; it is at least in a condition which is required. But 
when it is designed to effect important changes in the soil itself, as the liberation of the alka¬ 
lies, caustic and subcaustic lime is necessary. The quantity of caustic or subcaustic lime 
which is regarded as suitable, per acre, is not definitely settled. Two views on this question 
have been taken, and hence two plans have been adopted ; the first is, to lime heavily, and em¬ 
ploy it only at long intervals : on this plan 250 to 300 bushels of quicklime are allowed, per 
acre, where the lands are argillaceous; if the soil is siliceous 150 to 200 bushels are used. But the 
second plan admits only from 60 to 70 bushels, per acre, at intervals of seven or eight years. This 
* I deem it highly important that this statement should be repeated here. I have made the same elsewhere in this 
work; still writers frequently speak of calcareous soils, as if they had a real existence in this country. The state¬ 
ment is important, because real calcareous soils may be, and are treated very differently from other soils: for exam¬ 
ple, the astringent salts of iron may be employed with fine eflects on a calcareous soil. Now this salt of iron, (the 
proto-sulphate of iron) is especially injurious to vegetation. Where lime, however, is abundant in the soil, this 
poisonous salt is decomposed, the sulphuric acid leaves the iron and combines with the lime ; and hence a valuable 
fertilizer is at once formed in the soil, accompanied, as in the instance I have before stated, with the disengagement 
of carbonic acid. This is only one instance where a calcareous soil may be treated in a mode entirely different from 
any other kind of soil. Any of the New-York soils treated thus would be injured materially, and would not recover 
from the injury for years. 
